In cavity brick or block masonry construction, weep hole openings are left in mortar joints just above the flashing to allow both ventilation and drainage of the wall cavity between the exterior masonry and the interior wall. A weep hole opening is typically formed by the omission of mortar between two adjacent bricks or blocks. The weep hole opening provides ventilation and drainage to keep the wall cavity dry. Without adequate ventilation, dampness causes mildew and rot, which reduce the life of the structure.
Weephole openings vary considerably in size and shape dependent on the skill and care of the tradesmen and the type of brick and type of finishes being applied. A problem with weep hole openings situated close to ground level, as are common, is that they can become an entry for rodents and reptiles. Similarly, a problem with weep hole openings around windows or second floors is that they can provide an entry for insects. In particular, the weep hole opening leading to the wall cavity is an ideal home for bees, wasps and other insects, which themselves create food sources for other pests. Another problem associated with weep hole openings is that they provide an entry point for water, particularly during excessive rain or from garden sprinklers. Another problem with weep hole openings is that they can allow sparks and firebrands to penetrate a building.
There have been a number of known approaches which attempt to solve some of the above problems.
U.S. Pat. No. 4,282,691 (Risdon) discloses a weep hole device utilising a wick, tube and screen cap. U.S. Pat. No. 4,587,891 (Kruse) discloses a ventilating device that incorporates a tubular member and a screened bottom. UK Patent No. 2231889A (Knox) discloses a filter system for allowing drainage from trays in cavity wall.
U.S. Pat. No. 2,709,402 (Mahn) discloses a wall mounted ventilator using a series of parallel prongs as a fixing means. Australian Design Registration 131293 appears to disclose a similar device. U.S. Pat. No. 5,203,795 (Balamut et al) discloses a perforated wall plate and sealing gasket with an anchoring device.
U.S. Pat. No. 4,102,093 (Harris) discloses forcing a perforated sheet of aluminium into the weep hole opening and then using a special tool to deform the sheet to the shape of the opening.
The present applicants' earlier Australian Patent No. 713335, the entire disclosure of which is incorporated herein by reference, discloses a weep hole device including a hollow plastic body for engagement in a weep hole opening. A removable cover is provided over one end of the body to prevent mortar clogging the body during rendering. The cover is removed after rendering is complete and a vermin-proof grate is fitted onto the end of the body in its place. However, a problem with this device is that the grate cannot be installed until after rendering is complete and it is common for tradesmen to misplace the grate.
A problem with known weep hole devices, such as those mentioned above, is that they often fail as a result of being exposed to high temperatures, for example during bushfires. The failure can occur as a result of the weep hole device igniting and disintegrating, or due to the device melting, which allows fire brands and sparks, as well as vermin and insects, to enter the wall cavity.
Another problem with known weep hole devices is that they do not allow easy access to, or inspection of, the wall cavity.